Testing methods using spread-spectrum excitation signals and related test apparatus

Patent metadata

Field	Value
Publication number	US-10009121-B2
Application number	US-201715491069-A
Country	US
Kind code	B2
Filing date	Apr 19, 2017
Priority date	Apr 29, 2016
Publication date	Jun 26, 2018
Grant date	Jun 26, 2018

Abstract

According to methods of performing a passive inter-modulation distortion (“PID”) test, a first excitation signal and a second excitation signal are applied to a device under test, where at least one of the first and second excitation signals is a spread spectrum excitation signal. An output signal is received that includes a PID signal generated from mixing of the first and second excitation signals. At least a portion of the output signal is de-spread. A characteristic of the PID signal may then be measured.

First claim

That which is claimed is:

1. A method of performing a passive inter-modulation distortion (“PID”) test, the method comprising:
applying a first excitation signal and a second excitation signal to a device under test, where at least one of the first and second excitation signals is a spread spectrum excitation signal;
receiving an output signal that includes a PID signal generated from mixing of the first and second excitation signals;
de-spreading at least a portion of the output signal; and
measuring a characteristic of the PID signal.

2. The method of claim 1 , wherein the output signal includes a spread spectrum PID signal.

3. The method of claim 2 , wherein the at least the portion of the output signal that is de-spread comprises the spread spectrum PID signal.

4. The method of claim 1 , wherein the first RF excitation signal comprises a continuous wave radio frequency (RF) excitation signal and the spread spectrum excitation signal comprises a continuous wave RF signal that has had a first pseudo-random code sequence applied thereto.

5. The method of claim 4 , wherein de-spreading at least the portion of the output signal comprises applying the first pseudo-random code sequence to the output signal.

6. The method of claim 5 , further comprising spreading an interfering signal included in the output signal.

7. The method of claim 1 , further comprising down-converting the output signal prior to de-spreading at least the portion of the output signal.

8. The method of claim 7 , wherein down-converting the output signal comprises down-converting the output signal to a digitized base band signal.

9. The method of claim 7 , wherein down-converting the output signal comprises down-converting the output signal to an intermediate frequency signal having a frequency that is less than a frequency of the first excitation signal.

10. The method of claim 4 , wherein a chip rate of the pseudo-random code sequence is selected to generate a spread spectrum PID signal having a bandwidth that lies within a receive frequency bandwidth of the device under test.

11. The method of claim 1 , wherein the PID signal comprises a third order inter-modulation product of the first excitation signal and the second spread spectrum excitation signal, wherein a center frequency of the PID signal is a frequency that is twice a center frequency of the first excitation signal minus a center frequency of the second spread spectrum excitation signal.

12. The method of claim 11 , wherein a frequency of the first excitation signal is less than a center frequency of the second spread spectrum excitation signal.

13. The method of claim 11 , wherein a frequency of the first excitation signal is greater than a center frequency of the second spread spectrum excitation signal.

14. A method of performing a passive inter-modulation distortion (“PID”) test, the method comprising:
generating a first excitation signal;
applying a first pseudo-random code sequence to a second signal to generate a second spread spectrum excitation signal;
applying the first excitation signal and the second spread spectrum excitation signal to a device under test;
processing an output signal that is output from the device under test to generate a processed output signal;
applying the first pseudo-random code sequence to the processed output signal; and
measuring a characteristic of a PID signal included in the processed output signal.

15. The method of claim 14 , wherein the PID signal included in the processed output signal comprises a spread spectrum PID signal, and wherein applying the first pseudo-random code sequence to the processed output signal de-spreads the spread spectrum PID signal.

16. The method of claim 15 , wherein applying the first pseudo-random code sequence to the processed output signal further acts to convert an interfering signal included in the processed output signal into a spread spectrum interfering signal.

17. The method of claim 14 , wherein processing the output signal that is output from the device under test to generate a processed output signal comprises filtering the output signal based on a bandwidth of a receive frequency band of the device under test.

18. The method of claim 15 , wherein processing the output signal that is output from the device under test to generate a processed output signal comprises down-converting the output signal to one of baseband or an intermediate frequency that is between baseband and a frequency of the first excitation signal.

19. The method of claim 14 , wherein the first signal comprises a continuous wave excitation signal and the second excitation signal comprises a continuous wave signal.

20. A passive inter-modulation distortion (“PID”) test apparatus, comprising:
at least one signal generator that is configured to generate a first excitation signal and a second spread spectrum excitation signal;
a test apparatus that holds a device under test, the device under test configured to receive the first and second excitations signals from the at least one signal generator;
a receiver that is coupled to an output of the device under test so as to receive and down-convert an output signal that includes a PID signal generated by mixing of the first excitation signal and the second spread spectrum excitation signal;
a de-spreader that de-spreads the down-converted output signal; and
a signal analyzer that measures a characteristic of the de-spread down-converted output signal.

Assignees

• Commscope Technologies Llc

Inventors

• Vella-Coleiro George P
• Hou Xiaohua

Classifications

• H04B17/0085

  using test signal generators · CPC title

• G01R23/20 Primary

  Measurement of non-linear distortion · CPC title

• H04B17/00 Primary

  Monitoring; Testing (of line transmission systems H04B3/46; arrangements for monitoring or testing transmission systems employing electromagnetic waves other than radio waves H04B10/07) · CPC title

• H04B1/707

  using direct sequence modulation · CPC title